1. Field of the Invention
This invention generally relates to a method and an apparatus for recording data on a recording disc such as an optical disc. This invention particularly relates to a method and an apparatus for recording contents data such as audio data, video data, or audio-visual data on a rewritable DVD (digital versatile disc) in real time. In addition, this invention relates to a method and an apparatus for restoring data recorded on a recording disc such as a recordable or rewritable DVD. Furthermore, this invention relates to a computer program for restoring data recorded on a recording disc such as a recordable or rewritable DVD.
2. Description of the Related Art
DVDs are of several types including a rewritable type or a RAM type. The feature of a DVD of the rewritable type or the RAM type is that data can be recorded and reproduced thereon and therefrom a plurality of times.
The DVD-Video standards prescribe that during the recording of contents data on a DVD, management information inclusive of search information related to the contents data should also be recorded on the DVD. In general, contents data is divided into successive segments before being recorded on a DVD segment by segment. A management information piece is generated for every segment of the contents data. After the generation of a management information piece, a related contents-data segment and the management information piece are recorded on the DVD. Thus, the recording of a contents-data segment on the DVD remains inhibited until the preparations for recording a management information piece related to the contents-data segment are made. In other words, the preparations for recording the related management information piece are awaited. Such a waiting time causes a considerable delay in recording the contents data on the DVD. The recording delay deteriorates the real-time recording of the contents data.
In the event that the power feed to a DVD drive apparatus is interrupted during the recording of contents data on a DVD, a relatively great contents-data portion waiting to be recorded is lost due to the above-indicated recording delay.
U.S. Pat. No. 6,377,518 corresponding to Japanese patent application publication number P2002-530800A relates to a method of recording real-time information (video information) and control information related thereto in a recording area on a record carrier. The real-time information is subdivided into cells, and playback parameters for reproducing sequences of the cells are included in the control information. Within the recording area, the control information precedes the video information for playback functions of the recorded video. It is preferable that a recording is made in one pass, i.e., the video is to be recorded directly at its final location. Therefore, a recorder disclosed in U.S. Pat. No. 6,377,518 has a control unit for performing the following steps: first creating a free area by selecting a starting point within the recording area different from the beginning of the recording area, thereafter recording the real-time information from the starting point, and recording the control information in the free area.
In the method or the recorder of U.S. Pat. No. 6,377,518, the recording of control information related to real-time information causes a considerable delay in recording the real-time information.
Japanese patent application publication number P2003-109360A discloses a video recording and reproducing system including an optical disk drive and a hard disk drive. During a recording mode of operation of the system, the optical disk drive records audio-visual information and complete management information related thereto on a DVD while the hard disk drive periodically records partial management information (time map information) on a prescribed area in a hard disk for a backup purpose. The recording of the complete management information on the DVD follows the recording of the audio-visual information thereon. The management information is designed for managing the playback of the contents of the audio-visual information. In the event that the power feed to the system is interrupted during the recording mode of operation, partial management information remains in the prescribed area of the hard disk although complete management information related to currently-recorded audio-visual information fails to be recorded on the DVD. When the power feed to the system restarts, the partial management information is read out from the prescribed area of the hard disk and is then recorded on the DVD as complete management information related to the audio-visual information recorded up to the moment of the occurrence of the interruption of the power feed. Therefore, the recorded audio-visual information can be properly reproduced from the DVD by referring to the complete management information. In other words, it is possible to restore the audio-visual information recorded on the DVD.
In the system of Japanese application P2003-109360A, partial management information (time map information) is periodically recorded on the hard disk at intervals of, for example, one minute for a backup purpose. Thus, in the case where the moment of the occurrence of the interruption of the power feed is far away from the moment of the last recording of partial management information, a management information piece for a relatively-large end portion of audio-visual information recorded on the DVD fails to be backed up so that the relatively-large end portion of the recorded audio-visual information can not be restored. The system of Japanese application P2003-109360A tends to be high in cost due to the presence of the hard disk drive.
It is known to replace a hard disk drive with a nonvolatile memory such as a nonvolatile RAM in a system similar to that in Japanese application P2003-109360A. In this case, the presence of the nonvolatile memory causes the system to be high in cost.
There is a DVD recording apparatus equipped with a normal power supply and a backup power supply using a storage battery. In the event that the normal power supply fails, the backup power supply replaces the normal power supply to keep the recording of data on a DVD. The presence of the backup power supply causes the apparatus to be high in cost and heavy in weight.